1. Technical Field
The present invention relates to structural connectors and methods of reinforcing connection between structural members and active material wire actuators, and more particularly, to an assembly for and method of reinforcing connection that utilize the generation and engagement of an enlarged formation affixed to or formed within the actuator.
2. Background Art
Active material elements are conventionally utilized to effect reconfiguration and/or bias variance in structural assemblies, actuators or smart devices, when activated or deactivated. For example, shape memory alloy (SMA) wires are often used to transfer loads between and cause the displacements of structural members, upon activation. That is to say, once thermally activated, the crystal structure of the alloy reconfigures and in turn causes the wire to shrink; the actuating or reconfiguring force is transferred to the coupled members solely through their connection points. In promoting this function, it is appreciated that secure methods of joining (e.g., “connecting”) these wires to the structural members play a vital role.
Among conventional methods of joining, an O-ring brass ring crimp connector without insulation holder (FIG. 1) is widely used. This method, however, presents various concerns in the art. For example, slippage of the crimped portion of the wire during overload conditions (e.g., inertia loads on start-up from a cold stop, mechanical overload in the absence of an overload protection system, etc.) is a commonly experienced mal condition. Such failure, in turn, may cause the malfunction of the actuator or driven device. Of further concern is inconsistency and variability, and therefore, the inability to accurately predict failure in a given actuator. That is to say, it is appreciated by those of ordinary skill in the art that individual connections exhibit inconsistent load capacity as they undergo normal wear and tear (e.g., fatigue) over life, while the various conventional connectors exhibit differing capacities based on structural configuration.
Thus, for these reasons and more, there remains a need in the art for an improved method of joining active material elements, such as a shape memory wire, to structural members that increases structural capacity, and reduces the likelihood of premature failure.